[PATCH v2 01/10] workqueue: devres: Add device-managed allocate workqueue

[Krzysztof Kozlowski]

On 06/03/2026 05:08, Tejun Heo wrote:
> On Thu, Mar 05, 2026 at 10:45:40PM +0100, Krzysztof Kozlowski wrote:
>> Add a Resource-managed version of alloc_workqueue() to fix common
>> problem of drivers mixing devm() calls with destroy_workqueue.  Such
>> naive and discouraged driver approach leads to difficult to debug bugs
>> when the driver:
>>
>> 1. Allocates workqueue in standard way and destroys it in driver
>>    remove() callback,
>> 2. Sets work struct with devm_work_autocancel(),
>> 3. Registers interrupt handler with devm_request_threaded_irq().
>>
>> Which leads to following unbind/removal path:
>>
>> 1. destroy_workqueue() via driver remove(),
>>    Any interrupt coming now would still execute the interrupt handler,
>>    which queues work on destroyed workqueue.
>> 2. devm_irq_release(),
>> 3. devm_work_drop() -> cancel_work_sync() on destroyed workqueue.
>>
>> devm_alloc_workqueue() has two benefits:
>> 1. Solves above problem of mix-and-match devres and non-devres code in
>>    driver,
>> 2. Simplify any sane drivers which were correctly using
>>    alloc_workqueue() + devm_add_action_or_reset().
>>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski at oss.qualcomm.com>
> 
> Acked-by: Tejun Heo <tj at kernel.org>
> 
> Please let me know how you wanna route the patch.

Like I described in cover letter, so I propose this going via one tree,
e.g. power supply. The first patch might be needed for other trees as
well, e.g. if more drivers are discovered, so the best if it is on
dedicated branch in case it has to be shared just in case.

Does this look reasonable @Tejun, @Sebastian?

Best regards,
Krzysztof